The present invention relates to plural core transformers and, more particularly, to plural core transformers having divided primary windings therein.
In the design of medium and high power output, system transformers, such as low voltage system transformers in the range of from about 15 KVA and up, it is conventional to provide one or more laminated annular cores of ferromagnetic metallic material having openings therein and having one or more primary windings and one or more secondary windings positioned about more than one of the leg portions on one or more cores. The sizes of the openings in the annular metallic cores are, at least in a significant part, determined by the number of turns, by the cross-sectional areas of the conductors employed, and by the core legs occupied by the primary and secondary windings of the transformer.
Accordingly, the more turns that are required by the design, and the greater the cross-sectional area of the conductors that are required therein, the larger must be the openings in the annular metallic cores to accommodate the windings, and, therefore, the larger must be the overall size of the transformer. The ability of the transformer to dissipate heat generated therein decreases as the size of the transformer increases, as a result of the lower surface to volume ratio, yet at the same time the amount of heat generated increases.
The foregoing factors present significant problems in the design of low voltage system transformers of the types used in welding, brazing and bonding, and used in resistance heating and induction furnace systems. The reason for this is that such low voltage system transformers employ secondary windings of few turns in which the conductors thereof have large cross-sectional areas that require correspondingly large openings in the core metal to accommodate them. Thus, providing for efficient heat dissipation and compact size in low voltage system transformers represent an important design criteria for such transformers.
It is, therefore, an object of the present invention to provide low voltage system transformers having enhanced heat dissipation ability.
A further object of the present invention is to provide plural core, multi-magnetic field transformers that are more compact.
Yet another object of the present invention is to provide plural core multi-magnetic field transformers that are more economical to construct and operate than has heretofore been the case.
Further objects and advantages of this invention will become apparent as the following description proceeds.